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1. Field of the Invention
The present invention relates to a golf club head. More specifically, the present invention relates to a golf club head with an external frame composed of a high strength material and a body composed of a low density material.
2. Description of the Related Art
When a golf club head strikes a golf ball, large impacts are produced that load the club head face and the golf ball. Most of the energy is transferred from the head to the golf ball, however, some energy is lost as a result of the collision. The golf ball is typically composed of polymer cover materials (such as ionomers) surrounding a rubber-like core. These softer polymer materials having damping (loss) properties that are strain and strain rate dependent which are on the order of 10-100 times larger than the damping properties of a metallic club face. Thus, during impact most of the energy is lost as a result of the high stresses and deformations of the golf ball (0.001 to 0.20 inch), as opposed to the small deformations of the metallic club face (0.025 to 0.050 inch).
A more efficient energy transfer from the club head to the golf ball could lead to greater flight distances of the golf ball.
The generally accepted approach has been to increase the stiffness of the club head face to reduce metal or club head deformations. However, this leads to greater deformations in the golf ball, and thus increases in the energy transfer problem.
Some have recognized the problem and disclosed possible solutions. An example is Campau, U.S. Pat. No. 4,398,965, for a Method Of Making Iron Golf Clubs With Flexible Impact Surface, which discloses a club having a flexible and resilient face plate with a slot to allow for the flexing of the face plate. The face plate of Campau is composed of a ferrous material, such as stainless steel, and has a thickness in the range of 0.1 inches to 0.125 inches.
Another example is Eggiman, U.S. Pat. No. 5,863,261, for a Golf Club Head With Elastically Deforming Face And Back Plates, which discloses the use of a plurality of plates that act in concert to create a spring-like effect on a golf ball during impact. A fluid is disposed between at least two of the plates to act as a viscous coupler.
Yet another example is Jepson etal, U.S. Pat. No. 3,937,474, for a Golf Club With A Polyurethane Insert. Jepson discloses that the polyurethane insert has a hardness between 40 and 75 shore D.
Still another example is Inamori, U.S. Pat. No. 3,975,023, for a Golf Club Head With Ceramic Face Plate, which discloses using a face plate composed of a ceramic material having a high energy transfer coefficient, although ceramics are usually harder materials.
Chen et al., U.S. Pat. No. 5,743,813 for a Golf Club Head, discloses using multiple layers in the face to absorb the shock of the golf ball. One of the materials is a non-metal material.
Lu, U.S. Pat. No. 5,499,814, for a Hollow Club Head With Deflecting Insert Face Plate, discloses a reinforcing element composed of a plastic or aluminum alloy that allows for minor deflecting of the face plate which has a thickness ranging from 0.01 to 0.30 inches for a variety of materials including stainless steel, titanium, KEVLAR(copyright), and the like.
Yet another Campau invention, U.S. Pat. No. 3,989,248, for a Golf Club Having Insert Capable Of Elastic Flexing, discloses a wood club composed of wood with a metal insert.
Although not intended for flexing of the face plate, Anderson, U.S. Pat. Number 5,344,140, for a Golf Club Head And Method Of Forming Same, discloses use of a hot forged material for the face plate. The face plate of Anderson may be composed of several hot forged metal materials including steel, copper and titanium. The hot forged plate has a uniform thickness of between 0.090 and 0.1 30 inches.
Another invention directed toward forged materials in a club head is Su etal., U.S. Pat. No. 5,776,011 for a Golf Club Head. Su discloses a club head composed of three pieces with each piece composed of a forged material. The main objective of Su is to produce a club head with greater loft angle accuracy and reduce structural weaknesses. Aizawa, U.S. Pat. No. 5,346,216 for a Golf Club Head, discloses a face plate having a curved ball hitting surface.
U.S. Pat. No. 6,146,571 to Vincent, etal., discloses a method of manufacturing a golf club head wherein the walls are obtained by injecting a material such as plastic over an insert affixed to a meltable core. The core has a melt point lower than that of the injectable plastic material so that once the core is removed, an inner volume is maintained to form the inner cavity. The insert may comprise a resistance element for reinforcing the internal portion of the front wall of the shell upon removal of the core where the reinforcement element is comprised of aluminum with a laterally extending portion comprised of steel.
U.S. Pat. No. 6,149,534 to Peters, etal., discloses a golf club head having upper and lower metal engagement surfaces formed along a single plane interface wherein the metal of the lower surface is heavier and more dense than the metal of the upper surface.
U.S. Pat. Nos. 5,570,886 and 5,547,427 to Rigal, etal., disclose a golf club head of molded thermoplastic having a striking face defined by an impact-resistant metallic sealing element. The sealing element defines a front wall of the striking surface of the club head and extends upward and along the side of the impact surface to form a neck for attachment of the shaft to the club head. The sealing element preferably being between 2.5 and 5 mm in thickness.
U.S. Pat. No. 5,425,538 to Vincent, etal., discloses a hollow golf club head having a steel shell and a composite striking surface composed of a number of stacked woven webs of fiber.
U.S. Pat. No. 5,377,986 to Viollaz, etal., discloses a golf club head having a body composed of a series of metal plates and a hitting plate comprised of plastic or composite material wherein the hitting plate is imparted with a forwardly convex shape. Additionally, U.S. Pat. No. 5,310,185 to Violaz, etal., discloses a hollow golf club head having a body composed of a series of metal plates, a metal support plate being located on the front hitting surface to which a hitting plate comprised of plastic or composite is attached. The metal support plate has a forwardly convex front plate associated with a forwardly convex rear plate of the hitting plate thereby forming a forwardly convex hitting surface.
U.S. Pat. No. 5,1 06,094 to Desboilles, etal., discloses a golf club head having a metal striking face plate wherein the striking face plate is a separate unit attached to the golf club head with a quantity of filler material in the interior portion of the club head.
U.S. Pat. No. 4,568,088 to Kurahashi discloses a wooden golf club head body reinforced by a mixture of wood-plastic composite material. The wood-plastic composite material being unevenly distributed such that a higher density in the range of between 5 and 1 5 mm lies adjacent to and extends substantially parallel with the front face of the club head.
U.S. Pat. No. 4,021,047 to Mader discloses a golf club wherein the sole plate, face plate, heel, toe and hosel portions are formed as a unitary cast metal piece and wherein a wood or composite crown is attached to this unitary piece thereby forming a hollow chamber in the club head.
U.S. Pat. No. 5,624,331 to Lo, et al. discloses a hollow metal golf club head where the metal casing of the head is composed of at least two openings. The head also contains a composite material disposed within the head where a portion of the composite material is located in the openings of the golf club head casing.
U.S. Pat. No. 1,167,387 to Daniel discloses a hollow golf club head wherein the shell body is comprised of metal such as aluminum alloy and the face plate is comprised of a hard wood such as beech, persimmon or the like. The face plate is aligned such that the wood grain presents endwise at the striking plate.
U.S. Pat. No. 3,692,306 to Glover discloses a golf club head having a bracket with sole and striking plates formed integrally thereon. At least one of the plates has an embedded- elongate tube for securing a removably adjustable weight means.
U.S. Pat. No. 5,410,798 to Lo discloses a method of manufacturing a composite golf club head using a metal casing to which a laminated member is inserted. A sheet of composite material is subsequently layered over the openings of the laminated member and metal casing to close off the openings in the top of both. An expansible pocket is then inserted into the hollow laminated member comprising sodium nitrite, ammonium chloride and water causing the member to attach integrally to the metal casing when the head is placed into a mold and heated.
U.S. Pat. No. 4,877,249 to Thompson discloses a wood golf club head embodying a laminated upper surface and metallic sole surface having a keel. In order to reinforce the laminations and to keep the body from delaminating upon impact with an unusually hard object, a bolt is inserted through the crown of the club head where it is connected to the sole plate at the keel and tightened to compress the laminations.
U.S. Pat. No. 2,750,194 to Clark discloses a wooden golf club head with weight adjustment means. The golf club head includes a tray member with sides and bottom for holding the weight adjustment preferably cast or formed integrally with the heel plate. The heel plate with attached weight member is inserted into the head of the golf club via an opening.
U.S. Pat. No. 5,193,811 to Okumoto, et al. discloses a wood type club head body comprised primarily of a synthetic resin and a metallic sole plate. The metallic sole plate has on its surface for bonding with the head body integrally formed members comprising a hosel on the heel side, weights on the toe and rear sides and a beam connecting the weights and hosel. Additionally, U.S. Pat. No. 5,516,107 to Okumoto, et al., discloses a golf club head having an outer shell, preferably comprised of synthetic resin, and metal weight member/s located on the interior of the club head.
A foamable material is injected into the hollow interior of the club to form the core. Once the foamable material has been injected and the sole plate is attached, the club head is heated to cause the foamable material to expand thus holding the weight member/s in position in recess/es located in toe, heel and/or back side regions by pushing the weight member into the inner surface of the outer shell.
U.S. Pat. No. 4,872,685 to Sun discloses a wood type golf club head wherein a female unit is mated with a male unit to form a unitary golf club head. The female unit comprises the upper portion of the golf club head and is preferably composed of plastic, alloy, or wood. The male unit includes the structural portions of sole plate, a face insert consists of the striking plate and weighting elements. The male unit has a substantially greater weight being preferably composed of a light metal alloy. The units are mated or held together by bonding and or mechanical means.
U.S. Pat. No. 5,398,935 to Katayama discloses a wood golf club head having a striking face wherein the height of the striking face at a toe end of the golf club head is nearly equal to or greater than the height of the striking face at the center of the club head.
U.S. Pat. No. 1,780,625 to Mattern discloses a club head with a rear portion composed of a light-weight metal such as magnesium. U.S. Pat. No. 1,638,916 to Butchart discloses a golf club with a balancing member composed of persimmon or a similar wood material, and a shell-like body composed of aluminum attached to the balancing member.
Anderson, U.S. Pat. Nos. 5,024,437, 5,094,383, 5,255,918, 5,261,663 and 5,261,664 disclose a golf club head having a full body composed of a cast metal material and a face insert composed of a hot forged metal material.
Viste, U.S. Pat. No. 5,282,624 discloses a golf club head with a cast metal body and a forged steel face insert with grooves on the exterior surface and the interior surface of the face insert and having a thickness of 3 mm.
Rogers, U.S. Pat. No. 3,970,236, discloses an iron club head with a formed metal face plate insert fusion bonded to a cast iron body.
Aizawa, U.S. Pat. No. 5,242,168 discloses a golf club head having a fiber reinforced resin body with a thin metallic film layer.
Yamada, U.S. Pat. No. 4,535,990 discloses a golf club head having a fiber reinforced resin body with a face insert composed of a polycarbonate or like material.
Aizawa etal., U.S. Pat. No. 5,465,968 discloses a golf club head having a fiber reinforced resin body with a beryllium face plate.
The Rules of Golf, established and interpreted by the United States Golf Association (USGA) and The Royal and Ancient Golf Club of Saint Andrews, set forth certain requirements for a golf club head. The requirements for a golf club head are found in Rule 4 and Appendix II. A complete description of the Rules of Golf are available on the USGA web page at www.usga.org. Although the Rules of Golf do not expressly state specific parameters for a golf club face, Rule 4-1e prohibits the face from having the effect at impact of a spring with a golf ball. In 1998, the USGA adopted a test procedure pursuant to Rule 4-1e which measures club face COR. This USGA test procedure, as well as procedures like it, may bemused to measure club face COR.
Many existing high COR club heads utilize high strength titanium alloys and ultra high strength steel alloys welded to a compatible metal body. The edge of the face and the welding of the face to the body affects the COR and durability of the club head.
The elastic deflection of the face under the impact force of the ball is concentrated under the ball but extends to the edge of the face. The face under the ball and away from the impact experiences bending and stretching (tensile) strains. As long as the edge is relatively distant from the impact area the strains spread in a near uniform, dispersing pattern away from the ball. However, when the strains near the change in contour at the edge of the face, the distribution of the strains in the metal change in response to stiffness/constraint changes at the boundary. In existing clubs the edge is generally stiff and the deflection strains become concentrated stresses in the metal as the section of the metal changes from a thin plate to a near 90 degree bend. The section of the blend increases the stiffness, reduces the compliance and increases stress. In many cases, the local edge blend section experience only slight strains and through a combination of rigid body like rotation and translation pulls on (strains) the next geometric feature of the head such as the crown or sole. In these existing drivers, the closest boundary to the impact must be designed to survive the near impact. This limits the ability to design for compliance. The rounded edge shapes generally have good section stiffness. The local thickness can be reduced such that the club head will survive ball impact even at the face edge when the face material wraps around the face to create this edge. Many practical considerations limit the ability to thin or shape the structure at the edge of the face.
Existing drivers generally utilize a thick section and/or high strength material in the regions where the face first intersects the body blend to maintain acceptable durability. The thick sections reduce compliance and can adversely affect club head mass properties. Thin, high strength sections require compatible forming finishing and joining processes. These processes requirements add cost and can limit design form. Errors in the finishing and welding near the critical joints can reduce durability.
Although the prior art has disclosed many variations of multiple material club heads, the prior art has failed to provide a multiple material club head with a high coefficient of restitution and greater forgiveness for the typical golfer.
The present invention defines a new club head assembly and materials to create a multi-material club head that improves COR by providing lower constraint design options at the face edge and a broader use of materials away from the face.
One aspect of the present invention is a golf club head having a body composed of a lightweight material, a metal striking plate and a frame to provide an attachment means for the striking plate.
Another aspect of the present invention is a golf club head having a body, a striking plate and a frame. The body has a crown, a sole and a ribbon. The body also has an opening at a front end, a heel crown groove, a toe crown groove, a heel sole groove and a toe sole groove. The body is preferably composed of a thermoplastic material having a density less then 4.5 grams per cubic centimeter. The striking plate is positioned over the opening. The striking plate has a uniform thickness in the range of 0.040 inch to 0.250 inch. The striking plate has an upper heel hole, a lower heel hole, an upper toe hole and a lower toe hole. The striking plate insert is preferably composed of a metal material. The frame has a central body, an upper heel arm, a lower heel arm, an upper toe arm and a lower toe arm. The upper heel arm is positioned within the heel crown groove of the body to engage the upper heel hole of the striking plate. The lower heel arm is positioned within the heel sole groove of the body to engage the lower heel hole of the striking plate. The upper toe arm is positioned within the toe crown groove of the body to engage the upper toe hole of the striking plate. The lower toe arm is positioned within the toe sole groove of the body to engage the lower toe hole of the striking plate. The golf club head has a coefficient of restitution of 0.80 to 0.94, and the golf club head has a volume ranging from 300 cubic centimeters to 500 cubic centimeters.